Crack a forgotten password to hack a .dmg file?

I password protected a.dmg file ages ago and stupidly forgot the password but I know some of the numbers that could be in the password and I know of some words that could be in the password.

Are there any programs that could crack the password for me? For example a bruteforce program (for mac) where I load up the dictionary with my own items and it'll just go through them all in various combinations or however it works.

I would really appreciate any help it's got 513mb worth of really important information.

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